I found this when I was looking for ways to acclimate corals to the new bulbs.... RECYCLE YOUR OLD BULBS. Please do not throw them in the trash. Metal halide bulbs contain 5-7 times the amount of mercury of a fluorescent bulb. If you toss these bulbs into the trash, they will end up in landfills and eventually work their way into our groundwater where they can cause major problems. Manufacturers like IceCap work with Marine Depot and local fish clubs to gather used metal halide bulbs for recycling. Most cities also have recycling centers that accept used fluorescent bulbs and may take metal halides as well. Do you all recycle?? and if so where?
